Annealing Effect on Reactivity of Oxygen-Covered Au(111)

Abstract

We present results of an investigation into the effect of annealing on the reactivity of atomic oxygen adsorbed on Au(111) employing reactive molecular beam scattering (RMBS) and temperature-programmed desorption (TPD) techniques. Isotopically labeled water (e.g., H218O and D216O), carbon monoxide (CO), and oxygen-labeled carbon dioxide (C18O2) were used as probe molecules to investigate the reactivity of adsorbed oxygen. Our results show that the reactivity of atomic oxygen-precovered Au(111) is significantly altered by annealing. The annealed surfaces were prepared by depositing atomic oxygen (16O or 18O) at 77 K followed by annealing to temperatures ranging from 100−420 K before dosing probe molecules (H218O, CO, or C18O2) at 77 K. Without exception, annealing dramatically diminishes the reactivity of oxygen for all three probe reactions. In the case of the oxygen−water interactions, TPD indicates that annealing decreases the amount of oxygen isotope scrambling between oxygen and water. Additionally, t...